Introduction email to my host family

I am going to Japan in about 2 weeks and staying as a host student. Immediately working on an email to introduce myself but I feel like it's very blunt and too short, mainly because of my limited japanese skills. I've been trying to add kanji in order to make it more readable but I'm scared that will make them think I know more kanji than I really do. My draft is below, minus last names, but any suggestions of what to add/take away would be great. Thanks!

(***)家族のみなさんへ、
初めまして。私は(***)セーラです。どうぞよろしくおねがいします。私の日本語はかぎられた、でもあなたと話すことに興奮しています。私は17歳です。ケアリ高校に3年生です。家族は６人、父と母と兄と妹と弟です。私たちは二つ犬がいます。私の飛行機は遅くとおちゃくする、午後8時ごろ。ごめんこのメールはとても短いです,日本語と漢字は私にとっては難しい.福岡に着いたら、お会いできてうれしいです.

It looks fine to me - assuming that they already have the flight arrival details.

Just put the よろしく at the end; that's where it is supposed to be, and ending with nothing just looks weird. Other than that it's fine enough.

If you wrote perfect Japanese, the host family might assume that you are fluent in Japanese :) There are some places where I might prefer to use the polite (-desu/-masu) form instead of plain form.

If you want editing, comments, and some suggestions, assuming you are interested in learning the language, the following is what I can suggest, sentence by sentence.

(***)家族のみなさんへ、
OK, but you could also say ホストファミリーのみなさんへ

初めまして。私は(***)セーラです。Fine

どうぞよろしくおねがいします。
I will move this to the end, as suggested by Firas.

私の日本語はかぎられた、
I might switch to polite form - 私の日本語はかぎられています。Or you could rephrase to say (this かぎられた "...is limited" is quite literal) to say you are only a beginner in Japanese.

でもあなたと話すことに興奮しています。
興奮しています I am excited - I see what you mean, but we don't use this literal expression in Japanese. Also I would use みなさん instead of あなた to say "you."
でも、みなさんにメールを書くのは楽しいです。You could say "but I enjoy writing a mail to you"?)

私は17歳です。ケアリ高校に3年生です。
To say you are a junior OF Keari high school, we use の

家族は６人、父と母と兄と妹と弟です。
Fine

私たちは二つ犬がいます。
You've learned the "counter" for animals?

私の飛行機は遅くとおちゃくする、午後8時ごろ。
To say "arrives," とうちゃくします。A small hiragana error, and I would use polite form.

ごめんこのメールはとても短いです,
"gomen" is quite colloquial, maybe the bit longer form? The rest is fine.

日本語と漢字は私にとっては難しい.
Also you could use polite form?

福岡に着いたら、お会いできてうれしいです.
This sounds a bit like "I am happy to have met you," as if you already met. I might suggest: "I am looking forward to meeting you." You have learned that expression yet?